Isolation and characterization of pepsin fragments of laminin from human placental and renal basement membranes.
The presence of laminin in authentic basement membranes was examined at the level of a large pepsin-resistant fragment P1. This strongly antigenic fragment has been recently isolated from a mouse tumour basement membrane. By using antibodies to mouse laminin P1 for identification it was possible to isolate a homologous fragment P1 (Mr about 250 000) and a related component Pa (Mr about 70 000--90 000) from pepsin digests of human placenta and kidney. The fragments were in half-cystine (90--130 residues/1000) and carbohydrate and showed strong binding to concanavalin A. Reduction of disulphide bonds produced several smaller peptide chains, indicating a complex pepsin cleavage. Immunological assays demonstrated partial antigenic identity between laminin fragments obtained from mouse and human tissue, and suggested that fragment Pa may originate from a protein not completely identical with laminin. The results showed that laminin is an abundant component of tissue rich in basement membranes, which has been previously suggested by immunohistological studies.
D000596:Amino Acids / Q000032:analysis; D001485:Basement Membrane / Q000032:analysis; D003429:Cross Reactions; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006023:Glycoproteins / Q000276:immunology / Q000302:isolation & purification*; D006801:Humans; D007668:Kidney / Q000032:analysis*; D007797:Laminin; D008565:Membrane Proteins / Q000276:immunology / Q000302:isolation & purification*; D010434:Pepsin A / Q000378:metabolism; D010446:Peptide Fragments / Q000276:immunology / Q000302:isolation & purification; D010920:Placenta / Q000032:analysis*; D011247:Pregnancy; D011863:Radioimmunoassay
D000596:Amino Acids; D006023:Glycoproteins; D007797:Laminin; D008565:Membrane Proteins; D010446:Peptide Fragments; D010434:Pepsin A